1. Field of the Invention
The present invention relates to a photographing apparatus and a photographing method, and more particularly, to a photographing apparatus and a photographing method that can prevent a resolution at peripheral portions of an image from being degraded.
2. Description of the Related Art
In auto-focusing (AF) cameras which can perform auto-focus adjustment, when the focusing is performed based on a center of a photographing region, defocusing of peripheral portions of the photographing region can become worse due to aberrations in a photographing lens. Therefore, in Japanese Laid-open Patent No. 2006-189580, an average field curvature ratio, that is an average value of field curvature ratios with respect to an entire region of a photographing surface, is calculated, and the photographing lens is moved according to the average field curvature ratio.
However, in a case where a principal subject does not exist on the peripheral portion of the image, for example, when a general three-dimensional subject is photographed, there is no need to focus on the peripheral portion. In this case, defocusing of the peripheral portion can be required in order to emphasize the perspective of the subject. When the method of calculating the average field curvature ratio disclosed in the Japanese Laid-open Patent Publication No. 2006-189580 is applied, the processing needed to perform the photographing is excessively increased, and it thus requires much time to photograph the subject.
Also, in a case where a sheet of paper on which letters are printed is photographed, the center of the photographing region and the peripheral portion of the photographing region must be clearly focused, and thus, it is desirable to restrict degradation of resolution at the peripheral portions.